The Big Island, also known as Hawaii, is a favorite place for stargazers. Scientists from 11 countries work together at the 13,796-foot summit of Mauna Kea, a dormant volcano. It is also home to W.M. Keck Observatory and 13 of the world's largest optical and infrared telescopes. The twin Keck telescopes are each eight stories tall, weigh 300 tons and can track objects across the sky. On clear Hawaiian nights, scientists gather on the mountaintop to observe the universe. (MICHAEL DEFREITAS—GETTY IMAGES)